1. Field of the Invention
The present invention relates to a device for operating a pair of members to be operated, such as brake shoes in a drum brake, so as to be mechanically moved these members away from each other through the manipulation of a control lever, and in more detail, a device for detachably connecting a control cable to a free end of the control lever in this device.
2. Description of the Related Art
As to a control cable connecting device for the above mentioned operating device, there has been known, for example, a device as shown in FIGS. 16(a) and 16(b) for detachably connecting a brake cable with a free end of a control lever for operating a drum brake, which is disclosed in U.S. Pat. No. 5,311,793.
Referring to FIGS. 16(a) and 16(b), there are shown a pair of brake shoes 1, 2 as members to be operated, a pressing bracket 3, a control lever 4, and a brake cable 5 as a control cable, which are correlated with one another as explained as follows, so as to constitute an operating device 6 for a drum brake.
The pressing bracket 3 is formed at its one end with a cut-out 3a to which one of the brake shoes 1 is engaged, and the pressing bracket 3 is provided at the other end with the control lever 4 pivotally journalled at its proximal end by means of a pivot pin 7, while the control lever 4 is formed at the proximal end with a cut-out 4a to which the other brake shoe 2 is engaged.
The operating lever 4 is further formed at its free end with cut-outs 4b to which an end fitting 5a of the brake cable 5 is engaged in a cable pulling direction.
With this arrangement, when a cable pulling force is inputted to the control lever 4 through the brake cable 5, in the direction indicated by the arrow W, the control lever 4 is rotated around the pivot pin 7 in the corresponding direction to push the brake shoe 2 leftward in the figure.
Meanwhile, the above mentioned rotation of the control lever 4 around the pivot pin 7 applies a reaction force to the pressing bracket 3 through the intermediary of the pivot pin 7, and accordingly, the pressing bracket 3 is pushed rightward in the figure together with the brake shoe 1.
The brake shoes 1, 2, as a result of the above mentioned operation of moving away from each other thereof, are pressed against the inner peripheral surface of a brake drum which is not shown, and accordingly, a braking operation can be carried out.
By the way, the operating device 6 for a drum brake is preferably constituted in such manner that the brake cable 5 can be engaged with or disengaged from the cut-outs 4b of the control lever 4 while the drum brakes are incorporated in a use condition, and accordingly, the operating device 6 is further incorporated therein additionally with the following arrangement.
That is, as clearly shown in FIG. 16(b), the pressing bracket 3 is bifurcated, except the end part where the cut-out 3a is formed, so as to have a space which is defined by a pair of opposed leg parts 3b, 3c and an inner end wall 3d, in which space the control lever 4 is accommodated.
Further, the control lever 4 is also bifurcated, except the proximal end in which the pivot pin 7 and the cut-out 4a exist, so as to define a space between a pair of opposed leg parts 4c, 4d, though which space the brake cable 5 can pass.
However, the distance between the pair of opposed leg parts 4c, 4d is selected such that the end fitting 5a of the brake cable 5 cannot pass through the space between the opposed leg parts 4c, 4d, and the opposed leg parts 4c, 4d are formed respectively with the above mentioned cut-outs 4b for engaging the end fitting 5a of the control cable 5.
As clearly shown in FIG. 16(a), the distance between the free end face of the control lever 4 and the inner end wall 3d of the pressing bracket 3 is set to be such a size that the end fitting 5a of the control cable 5 can pass through a gap between the free end face of the control lever 4 and the inner end wall 3d of the pressing bracket 3, and a V-shaped leaf spring 8 is interposed so as to block the above gap, one leg part 8a of which V-shaped leaf spring 8 being made into close contact with the inner end wall 3d.
The other leg part 8b of the V-shaped leaf spring 8 is made into close contact with the free end face of the control lever 4 to define a wedge-like space 9 between the leg part 8b of the V-shaped leaf spring 8 and the free end face of the control lever 4, which wedge-like space 9 guides the end fitting 5a of the brake cable 5 upon insertion which will be explained hereinafter.
When the brake cable 5 is to be engaged the free end of the control lever 4, the end fitting 5a of the brake cable 5, as indicated by the two-dot chain line in FIG. 16(a), is at first inserted into the above mentioned wedge-like space 9 from the outside of the drum brake, and then, the brake cable 5 and its end fitting 5a are pushed further as indicated by the arrow .alpha..
At this time, the end fitting 5a is further advanced while being supported against the free end face of the control lever 4 and elastically deforming the sprig leg part 8b of the V-shaped leaf spring 8 in a direction indicated by the arrow .beta.. When the end fitting 5a overrides the free end face of the control lever 4, the end fitting 5a is pushed by elastic restoration of the spring leg part 8b in a direction reverse to the direction indicated by the arrow .beta. so that the end fitting 5a is engaged with the cut-outs 4b.
It is noted that this elastic restoration of the spring leg part 8b can prevent the end fitting 5a of the brake cable 5 from disengaging from the free end of the control lever 4.
When the brake cable 5 is to be removed, the spring leg part 8b of the V-shaped leaf spring 8 is elastically deformed in the direction indicated by the arrow .beta. from the outside of the drum brake with use of a suitable tool, and in this condition, in reverse order of the above mentioned steps, the end fitting 5a of the brake cable 5 is disengaged from the cut-outs 4b, and then the brake cable 5 is pulled out of the drum brake with its end fitting 5a.
By the way, in the above mentioned conventional device for connecting the control cable for the drum brake, since the end fitting 5a of the brake cable is allowed to pass through the gap between the free end face of the control lever 4 and the inner end wall 3d of the pressing bracket 3 so as to engage or disengage the brake cable 5, and further, since it is necessary to normally block this gap with the V-shaped leaf spring 8 in order to prevent the end fitting 5a of the brake cable 5 from disengaging from the free end of the control lever 4, the gap between the free end face of the control lever 4 and the inner end wall 3d of the pressing bracket 3, as indicated by A in FIG. 16(a), should be set to a size which is obtained by adding gap required for passing of the end fitting 5a to the value twice as large as the thickness of the V-shaped leaf spring 8. Accordingly, there has been a problem such that the overall length of the operating device 6 becomes longer, and further, there has been a problem such that additional components including the V-shaped leaf spring 8 should be incorporated to be economically disadvantageous.
Furthermore, the brake cable 5 is likely to buckle when the brake cable 5 is pushed into the wedge-like space 9 for engaging the end fitting 5a of the brake cable 5 to the free end of the control lever 4, and accordingly, since careful working is required in order to prevent occurrence of this buckling, and further, since it is required to elastically deform the spring leg part 8b of the V-shaped leaf spring 8 when the end fitting 5a of the brake cable 5 is detached from the free end of the control lever 4, as well as this working requiring a tool inserted from the outside of the drum brake, there has been inevitably presented such a problem that the engagement and the disengagement of the end fitting 5a of the brake cable 5 become more difficult.